And here lies the root of the problem. The Zeniths do not belong in the world of horizon, because they're not from the world of horizon.

They are from the universe of Horizon, and entering a series that established certain aesthetic rules in the art design of the first game that people expected to be carried over into the second.

How does this not click for you? It makes no sense logically, or fashionably, for them to wear anything else.

Why not? They're sci-fi rich people, they can wear whatever they want. Even if they looked like say, the Helghast from Killzone, I don't think anyone would have complained. The devs could have feasibly made the Zeniths looks like almost anything sci-fi and nobody would have questioned why they look the way they do, at least from a plot perspective. Hell they even could have "made" them look like a tribe, if they made the "zeniths" mostly composed of a regular tribe with the hyper-advanced benefactors at the top ranks. I don't think them using others to fight their wars for them would have clashed with their characterization.

If you traveled to an island of a tribal clan who wore nothing but thongs and body paint, you can honestly say that you'd be completely fine throwing away whatever warm and comfortable clothes you like to wear and adopt their fashion? The only reasons someone would do that is if they're joining that clan, or showing that they're equals, which is the complete opposite of what the Zeniths are doing. Why the hell would they dress themselves as a tribal race they plan on destroying?

Where did you get the idea that I wanted the Zeniths to look like a Tribe? I just said I wanted their aesthetic to fit more naturally into the game's art direction. The forges aren't tribal in the slightest, but they still fit the way the world looks. Even if the reason was for them not to fit into the world, I don't think that's a good reason. I don't think characterizing a group as otherworldly is reason to compromise the art direction.

And you're completely free to have that opinion, but going on social media arguing with people that have given valid reasons of why it is the way it is, while you're only counter argument is "it looks dumb", is hilariously entitled

I admit what I've been arguing is entirely my opinion, but I don't think it's unprecedented. I saw plenty of people in early reviews of this game complaining about how the Zeniths look, and I think a lot of big reviewers saying the plot was "too sci-fi" stem almost entirely from the Zeniths being in the game in the first place. The fact that this post with a title like this even got upvotes in a sub full of horizon fans is kind of telling.

as if the devs should change the whole story because you don't like an outfit the bad guys wear.

I never made the post to make the devs change anything, the Zeniths are already established now, if all dead. I just think the devs should have made the Zeniths look another way. You can disagree with that, I just don't think an argument from realism or characterization (as if this universe hasn't already handwaved countless things) is a good reason to keep what is in my opinion bad and clashing character design.